If you’re a yoga teacher that has access to the internet, chances are, you come across articles of the “How To Cure Sciatica With Yoga” variety with some regularity. Sciatica is often thought to be caused by the piriformis, one of the six external rotators of the hip, becoming hypertonic and compressing the sciatic nerve, resulting in pain in the back of the leg. Setting aside these articles’ tendency to conveniently over-simplify a potentially more complex condition*, I was also initially confused by the poses that were invariably suggested: pigeon, Ardha Matsyendrasana, and Gomukhasana. In other words, poses that externally rotate the hip. While there’s no denying that most people will feel a stretch in the appropriate gluteal region in these poses, I couldn’t quite wrap my head around the actual mechanics that allegedly produced the stretch. Namely: if the piriformis is an external rotator of the hip, how do externally rotated poses such as pigeon produce a stretch, rather than a contraction?

This is where it’s useful to understand a little bit of the anatomy of the piriformis. The muscle has its origin on the anterior part of the sacrum, the superior margin of the greater sciatic notch, and the sacroiliac joint capsule. It inserts on the greater trochanter of the femur. Imagine a hip joint in a neutral position, put your 3D visualization skills to work, and it’s easy to see how a contraction of the piriformis causes the hip to externally rotate. Here’s the thing: the function of the piriformis also depends on the position of the hip, and Pigeon, Ardha Matsyendrasana and Gomukhasana all put the hip into a flexed position. This changes the position of the piriformis’ origin and insertions points relative to each other, effectively turning the piriformis into an internal rotator when the hip is in flexion. So, it’s the combination of flexion and external rotation is what makes our traditional hip openers such effective stretches for the piriformis. It’s also worth noting that this reversal in function is far more than just an interesting detail. Indeed, it’s crucial even to the simple action of walking: when the hip flexes and the leg lifts in preparation for stepping forward, the piriformis internally rotates the hip and abducts the femur, shifting weight to opposite foot and preventing us from falling over.

So: back to stretching the piriformis! As discussed, the effectiveness of the stretch depends on our ability to move the muscle’s origin (at the sacrum) as far as possible from its insertion (the greater trochanter of the femur). We also need need to make sure the stretch is, in fact, isolated to the hip: if the lumbar spine is flexed, the stretch moves out of the hip and becomes less effective. It’s also worth noting that the piriformis plays an important role in stabilizing the sacrum, so it’s important to try to get an even stretch on both sides: asymmetries between left and right can contribute to sacral imbalances, which then translate up into the spinal column (no bueno).

One of my favorite poses for accessing the piriformis is this variation on reclined pigeon. Using the wall takes any unnecessary effort out of the pose, allowing the student to focus on isolating the stretch to the relevant area, and the floor provides a helpful cue for flattening the lumbar. Here’s how:

Face the wall and scoot yourself about a shin’s length away from it. Lay down and come into reclined pigeon: cross the left ankle just above the right knee, flexing the left foot. Place the sole of the right foot on the wall; since we’re working on the left hip, this will help you to take the right leg out of the equation. Gently press the left knee towards the wall, provided there’s no discomfort in the knee joint itself.

Notice if your lower back is rounding (the tailbone will be lifting away from the floor). Try to flatten the lumbar; the floor will provide a helpful reference point here for less mobile yogis. If the low back is resisting, or you just feel as though your stretch is maxed out, stay here.

If you can easily flatten the low back onto the floor, try taking the stretch one step further. Maintain external rotation in the left hip by moving the knee towards the wall, and arch your lower back, lifting it away from the floor. This moves the attachment points of the piriformis further away from each other still. Aside from the more obvious, superficial stretch in the outer hip, notice the more subtle increase in sensation deep under the main, fleshy part of the glutes. Stay and hold for as long as you like, then repeat on the other side.